The Protein Production Core (Core B) will produce and provide high quality antigens (different variants of gp41-54-GHC) and costimulatory molecules to Projects 1 and 2. The specific aims are: Aim 1. To produce high quality gp41 MPER-based antigens. A major responsibility of this Core is to provide sufficient amount of different variants of gp41-MPER antigens to Project 1 for preparation of multivalent antigens on gold nanoparticles (GNP) and DNA matrix, and for encapsulation in polyanhydride nanoparticles. Recombinant proteins will also be provided to Project 2 for conducting necessary immunoassays to assess B cell responses (e.g. ELISA, ELISPOT, antigen-specific B cell labeling). New recombinant protein constructs will be generated as needed. Antigens will be expressed, purified, and their quality will be carefully monitored prior to usage in Projects 1 and 2. Aim 2. To produce high quality immune effector molecules. Costimulatory molecules CD154 (CD40L) and BLyS will be used to enhance B cell responses by co-presenting them with antigens to B cells either as free proteins or complexed to GNP or DNA matrix. CDI 54 and BLyS will be loaded onto GNP and DNA matrix in Project 1. Alternatively, they can be used directly as soluble proteins (Project 2). Structural and functional integrity of the proteins will be evaluated prior to usage in Projects 1 and 2.